<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <p><input type="text"><button>添加</button></p>

</body>
</html>

<script>
    let ipt=document.querySelector('input')
    let btn = document.querySelector('button')
    let str=''
    let list = 
    btn.onclick=
</script>